1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PAGEWALK_H 2 #ifndef _LINUX_PAGEWALK_H
3 #define _LINUX_PAGEWALK_H 3 #define _LINUX_PAGEWALK_H
4 4
5 #include <linux/mm.h> 5 #include <linux/mm.h>
6 6
7 struct mm_walk; 7 struct mm_walk;
8 8
9 /* Locking requirement during a page walk. */ <<
10 enum page_walk_lock { <<
11 /* mmap_lock should be locked for read <<
12 PGWALK_RDLOCK = 0, <<
13 /* vma will be write-locked during the <<
14 PGWALK_WRLOCK = 1, <<
15 /* vma is expected to be already write <<
16 PGWALK_WRLOCK_VERIFY = 2, <<
17 }; <<
18 <<
19 /** 9 /**
20 * struct mm_walk_ops - callbacks for walk_pag 10 * struct mm_walk_ops - callbacks for walk_page_range
21 * @pgd_entry: if set, called for eac 11 * @pgd_entry: if set, called for each non-empty PGD (top-level) entry
22 * @p4d_entry: if set, called for eac 12 * @p4d_entry: if set, called for each non-empty P4D entry
23 * @pud_entry: if set, called for eac 13 * @pud_entry: if set, called for each non-empty PUD entry
24 * @pmd_entry: if set, called for eac 14 * @pmd_entry: if set, called for each non-empty PMD entry
25 * this handler is requir 15 * this handler is required to be able to handle
26 * pmd_trans_huge() pmds. 16 * pmd_trans_huge() pmds. They may simply choose to
27 * split_huge_page() inst 17 * split_huge_page() instead of handling it explicitly.
28 * @pte_entry: if set, called for eac 18 * @pte_entry: if set, called for each PTE (lowest-level) entry,
29 * including empty ones 19 * including empty ones
30 * @pte_hole: if set, called for eac 20 * @pte_hole: if set, called for each hole at all levels,
31 * depth is -1 if not kno 21 * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD.
32 * Any folded depths (whe 22 * Any folded depths (where PTRS_PER_P?D is equal to 1)
33 * are skipped. 23 * are skipped.
34 * @hugetlb_entry: if set, called for eac 24 * @hugetlb_entry: if set, called for each hugetlb entry. This hook
35 * function is called wit 25 * function is called with the vma lock held, in order to
36 * protect against a conc 26 * protect against a concurrent freeing of the pte_t* or
37 * the ptl. In some cases 27 * the ptl. In some cases, the hook function needs to drop
38 * and retake the vma loc 28 * and retake the vma lock in order to avoid deadlocks
39 * while calling other fu 29 * while calling other functions. In such cases the hook
40 * function must either r 30 * function must either refrain from accessing the pte or
41 * ptl after dropping the 31 * ptl after dropping the vma lock, or else revalidate
42 * those items after re-a 32 * those items after re-acquiring the vma lock and before
43 * accessing them. 33 * accessing them.
44 * @test_walk: caller specific callba 34 * @test_walk: caller specific callback function to determine whether
45 * we walk over the curre 35 * we walk over the current vma or not. Returning 0 means
46 * "do page table walk ov 36 * "do page table walk over the current vma", returning
47 * a negative value means 37 * a negative value means "abort current page table walk
48 * right now" and returni 38 * right now" and returning 1 means "skip the current vma"
49 * Note that this callbac 39 * Note that this callback is not called when the caller
50 * passes in a single VMA 40 * passes in a single VMA as for walk_page_vma().
51 * @pre_vma: if set, called before 41 * @pre_vma: if set, called before starting walk on a non-null vma.
52 * @post_vma: if set, called after a 42 * @post_vma: if set, called after a walk on a non-null vma, provided
53 * that @pre_vma and the 43 * that @pre_vma and the vma walk succeeded.
54 * 44 *
55 * p?d_entry callbacks are called even if thos 45 * p?d_entry callbacks are called even if those levels are folded on a
56 * particular architecture/configuration. 46 * particular architecture/configuration.
57 */ 47 */
58 struct mm_walk_ops { 48 struct mm_walk_ops {
59 int (*pgd_entry)(pgd_t *pgd, unsigned 49 int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
60 unsigned long next, s 50 unsigned long next, struct mm_walk *walk);
61 int (*p4d_entry)(p4d_t *p4d, unsigned 51 int (*p4d_entry)(p4d_t *p4d, unsigned long addr,
62 unsigned long next, s 52 unsigned long next, struct mm_walk *walk);
63 int (*pud_entry)(pud_t *pud, unsigned 53 int (*pud_entry)(pud_t *pud, unsigned long addr,
64 unsigned long next, s 54 unsigned long next, struct mm_walk *walk);
65 int (*pmd_entry)(pmd_t *pmd, unsigned 55 int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
66 unsigned long next, s 56 unsigned long next, struct mm_walk *walk);
67 int (*pte_entry)(pte_t *pte, unsigned 57 int (*pte_entry)(pte_t *pte, unsigned long addr,
68 unsigned long next, s 58 unsigned long next, struct mm_walk *walk);
69 int (*pte_hole)(unsigned long addr, un 59 int (*pte_hole)(unsigned long addr, unsigned long next,
70 int depth, struct mm_w 60 int depth, struct mm_walk *walk);
71 int (*hugetlb_entry)(pte_t *pte, unsig 61 int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
72 unsigned long add 62 unsigned long addr, unsigned long next,
73 struct mm_walk *w 63 struct mm_walk *walk);
74 int (*test_walk)(unsigned long addr, u 64 int (*test_walk)(unsigned long addr, unsigned long next,
75 struct mm_walk *walk); 65 struct mm_walk *walk);
76 int (*pre_vma)(unsigned long start, un 66 int (*pre_vma)(unsigned long start, unsigned long end,
77 struct mm_walk *walk); 67 struct mm_walk *walk);
78 void (*post_vma)(struct mm_walk *walk) 68 void (*post_vma)(struct mm_walk *walk);
79 enum page_walk_lock walk_lock; <<
80 }; 69 };
81 70
82 /* 71 /*
83 * Action for pud_entry / pmd_entry callbacks. 72 * Action for pud_entry / pmd_entry callbacks.
84 * ACTION_SUBTREE is the default 73 * ACTION_SUBTREE is the default
85 */ 74 */
86 enum page_walk_action { 75 enum page_walk_action {
87 /* Descend to next level, splitting hu 76 /* Descend to next level, splitting huge pages if needed and possible */
88 ACTION_SUBTREE = 0, 77 ACTION_SUBTREE = 0,
89 /* Continue to next entry at this leve 78 /* Continue to next entry at this level (ignoring any subtree) */
90 ACTION_CONTINUE = 1, 79 ACTION_CONTINUE = 1,
91 /* Call again for this entry */ 80 /* Call again for this entry */
92 ACTION_AGAIN = 2 81 ACTION_AGAIN = 2
93 }; 82 };
94 83
95 /** 84 /**
96 * struct mm_walk - walk_page_range data 85 * struct mm_walk - walk_page_range data
97 * @ops: operation to call during the w 86 * @ops: operation to call during the walk
98 * @mm: mm_struct representing the tar 87 * @mm: mm_struct representing the target process of page table walk
99 * @pgd: pointer to PGD; only valid wit 88 * @pgd: pointer to PGD; only valid with no_vma (otherwise set to NULL)
100 * @vma: vma currently walked (NULL if 89 * @vma: vma currently walked (NULL if walking outside vmas)
101 * @action: next action to perform (see en 90 * @action: next action to perform (see enum page_walk_action)
102 * @no_vma: walk ignoring vmas (vma will a 91 * @no_vma: walk ignoring vmas (vma will always be NULL)
103 * @private: private data for callbacks' us 92 * @private: private data for callbacks' usage
104 * 93 *
105 * (see the comment on walk_page_range() for m 94 * (see the comment on walk_page_range() for more details)
106 */ 95 */
107 struct mm_walk { 96 struct mm_walk {
108 const struct mm_walk_ops *ops; 97 const struct mm_walk_ops *ops;
109 struct mm_struct *mm; 98 struct mm_struct *mm;
110 pgd_t *pgd; 99 pgd_t *pgd;
111 struct vm_area_struct *vma; 100 struct vm_area_struct *vma;
112 enum page_walk_action action; 101 enum page_walk_action action;
113 bool no_vma; 102 bool no_vma;
114 void *private; 103 void *private;
115 }; 104 };
116 105
117 int walk_page_range(struct mm_struct *mm, unsi 106 int walk_page_range(struct mm_struct *mm, unsigned long start,
118 unsigned long end, const struc 107 unsigned long end, const struct mm_walk_ops *ops,
119 void *private); 108 void *private);
120 int walk_page_range_novma(struct mm_struct *mm 109 int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
121 unsigned long end, c 110 unsigned long end, const struct mm_walk_ops *ops,
122 pgd_t *pgd, 111 pgd_t *pgd,
123 void *private); 112 void *private);
124 int walk_page_range_vma(struct vm_area_struct 113 int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start,
125 unsigned long end, con 114 unsigned long end, const struct mm_walk_ops *ops,
126 void *private); 115 void *private);
127 int walk_page_vma(struct vm_area_struct *vma, 116 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
128 void *private); 117 void *private);
129 int walk_page_mapping(struct address_space *ma 118 int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
130 pgoff_t nr, const struct 119 pgoff_t nr, const struct mm_walk_ops *ops,
131 void *private); 120 void *private);
132 <<
133 typedef int __bitwise folio_walk_flags_t; <<
134 <<
135 /* <<
136 * Walk migration entries as well. Careful: a <<
137 * concurrently. <<
138 */ <<
139 #define FW_MIGRATION ((__fo <<
140 <<
141 /* Walk shared zeropages (small + huge) as wel <<
142 #define FW_ZEROPAGE ((__fo <<
143 <<
144 enum folio_walk_level { <<
145 FW_LEVEL_PTE, <<
146 FW_LEVEL_PMD, <<
147 FW_LEVEL_PUD, <<
148 }; <<
149 <<
150 /** <<
151 * struct folio_walk - folio_walk_start() / fo <<
152 * @page: exact folio page referenced (i <<
153 * @level: page table level identifying t <<
154 * @pte: pointer to the page table entr <<
155 * @pmd: pointer to the page table entr <<
156 * @pud: pointer to the page table entr <<
157 * @ptl: pointer to the page table lock <<
158 * <<
159 * (see folio_walk_start() documentation for m <<
160 */ <<
161 struct folio_walk { <<
162 /* public */ <<
163 struct page *page; <<
164 enum folio_walk_level level; <<
165 union { <<
166 pte_t *ptep; <<
167 pud_t *pudp; <<
168 pmd_t *pmdp; <<
169 }; <<
170 union { <<
171 pte_t pte; <<
172 pud_t pud; <<
173 pmd_t pmd; <<
174 }; <<
175 /* private */ <<
176 struct vm_area_struct *vma; <<
177 spinlock_t *ptl; <<
178 }; <<
179 <<
180 struct folio *folio_walk_start(struct folio_wa <<
181 struct vm_area_struct *vma, un <<
182 folio_walk_flags_t flags); <<
183 <<
184 #define folio_walk_end(__fw, __vma) do { \ <<
185 spin_unlock((__fw)->ptl); \ <<
186 if (likely((__fw)->level == FW_LEVEL_P <<
187 pte_unmap((__fw)->ptep); \ <<
188 vma_pgtable_walk_end(__vma); \ <<
189 } while (0) <<
190 121
191 #endif /* _LINUX_PAGEWALK_H */ 122 #endif /* _LINUX_PAGEWALK_H */
192 123
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